JPS605489Y2 - tire pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire air pressure sensor that is attached to an air valve of a tire to detect when the air pressure of the tire deviates from a predetermined allowable range.

The tire air pressure sensor according to the present invention is suitable for forming a tire air pressure alarm device together with a dry battery and a buzzer placed in the center of a road wheel of a tire, and detects when the tire air pressure has decreased below a predetermined value. This device automatically activates a buzzer, and the buzzer sound is used to notify abnormal decreases in tire air pressure.

However, as shown in FIG. 1, conventionally, this type of tire air pressure sensor is attached to an air valve 1 of a tire, and when the tire air pressure abnormally decreases, the pressing force of a spring 2 causes a movable element 3 to close a fixed contact on a base plate 4. The switch is operated by being pressed and in contact with the movable element, but the manufacturing process of the movable element 3, which is the main part on the movable side, and the hollow shaft 5, which guides the movable element 3 and acts as a conductor, is complicated. It was made up of expensive parts.

That is, as shown in FIG. 2, the movable element 3 forming a contact point on the movable side that turns on when the air pressure of the tire abnormally decreases, and the hollow shaft 5 that guides and holds the movable element 3, are connected to the movable element 3 as shown in FIG.
The hollow shaft 5 has a cylindrical protrusion 3a in the center and contacts 3b are formed on both sides by cutting, for example, a conductive metal. One end corresponding to the movable element 3 is provided with an i5a, into which the movable element 3 is inserted so as to be movable forward and backward, and further provided with a mounting groove 5b for fixing the contact plate 6.

Furthermore, the other end has a stepped finish with an outer diameter narrower than that of the one end, and the hollow hole 5c is provided with an adjusting screw 7 for adjusting the strength of the spring 2 inserted into the hollow hole 5c. Screw processing is done for screwing together.

Contact point 3b of mover 3 forming the contact point on the movable side having the above configuration
, the contacts 6a of the contact plate 6 must be made of a conductive material because the three points must be electrically connected to each other when they contact the respective fixed contacts of the corresponding board 4,
Due to the complexity of the shape, parts processing is expensive, and furthermore, there is a limit to miniaturization, and the overall size of the product is determined accordingly.

This invention was devised in view of the above problems, namely:
By changing the connection configuration between the movable element 3 and the contacts on the movable side, which were configured through conduction between the movable element 3 and the hollow shaft 5, to a configuration in which the movable element and the contact plate are used, manufacturing of these component parts becomes easier. It is also an object of the present invention to provide an inexpensive tire air pressure sensor that can be made smaller.

Hereinafter, preferred embodiments of the tire air pressure sensor according to the present invention will be described in detail based on FIGS. 3, 4, 5, 6, and 7.

The main body 8 is rotatably equipped with a ring nut 9 on one circumference, and the main body 8 is attached to the air valve 10 of the tire by screwing the ring nut 9 into the air valve 10 of the tire.

The main body 8 also includes lead wires 22, 23, and 24.
The peripheral edge 8b from which the insertion portion 8a has been removed is bent, and the flange lla at one end of the insulating cylinder 11 is crimped and fixed to the peripheral edge 8b.

At this time, a rubber diaphragm 12 and a printed circuit board 13 are held between the main body 8 and the cylindrical body 11.

The rubber diaphragm 12 is compressed and fitted into the stepped opening 8c of the main body 8, and the cylindrical body 11 is connected to the main body 8 by a packing action.
The printed circuit board 13 is fitted into the stepped opening 8d of the main body 8, and the cylinder body 11 is
It is held in a container.

Reference numeral 14 denotes a hollow shaft made of an insulating material, which is disposed so as to be able to move forward and backward within the cylindrical body 11 and rotatable within a range of 45 degrees.
6 is fixed.

The forward and backward movement of the hollow shaft 14 is regulated by the hemispherical protrusion 14b protruding from the shoulder 14a and the shoulder 11b of the cylindrical body 11, and the rotation of the hollow shaft 14 is regulated by the hollow shaft 14.
a recess 14c provided at a predetermined angle in the shoulder portion 14a of the
The rotation range is restricted to 45° by the stopper 11c of the cylinder 11 that engages with the recess 14c.

Reference numeral 17 denotes an adjustment screw screwed onto the cylindrical body 11, which connects the contact 18a of the movable element 18 that engages with the hollow shaft 14 in the rotational direction to each fixed contact 13b of the printed circuit board 13.
, 13c, and the movable pin 1 supported by the movable element 18
The other end of the spring 2 passes through the hole 13a in the center of the printed circuit board 13 and connects to the rubber diaphragm 12.
0, and the strength of the pressing force is determined by adjusting screw 1.
It is set by adjusting the screw position in step 7.

As shown in FIG. 6, the movable element 18 is formed by bending a thin plate made of a conductive material into a U-shape by pressing or the like, and has a hole 18b in the center thereof into which a movable pin is fitted. At the same time, contacts 18b, 18b are provided on both sides of the hole 18b.
is formed with a protrusion.

Furthermore, both bent ends of the movable element 18 are inserted into recesses 14d, 14d bored in the other peripheral wall of the hollow shaft 14.

Further, the movable pin 19 is made of an insulating material, and has a wire 119a wound around the end thereof, and the outer diameter of the movable pin 19 is tapered in a tapered shape, and a vertical groove 19b is cut in the axial direction. , care is taken to ensure that the movable element 18 is properly fitted into the hole 18b.

The movable element 18, which is fitted and integrated with the movable pin 19, is inserted into the recess 14d of the other peripheral wall of the hollow shaft 14 so as to be able to move forward and backward.
is engaged in.

Reference numeral 21 designates a contact plate for checking, which is made of a conductive elastic material and has an annular arm 21a on its outer periphery and a contact 21b at its free end.

The contact plate 21 is crimped and fixed to the other end surface of the hollow shaft 14 by a protrusion 14e that projects integrally therewith.

At this time, the contact 21b of the arm portion 21a is separated from the fixed contact 13d of the opposing printed circuit board with a predetermined gap maintained therebetween.

Further, the protrusion 14b of the shoulder 14a of the hollow shaft 14 is pressed against the shoulder 11b of the cylinder 11 by the repulsive force of the spring 20, and the contact plate 2 fixed to the other end surface of the hollow shaft 14 is pressed against the shoulder 11b of the cylinder 11.
1 and the back surface 18c of the movable element 18 on the opposite side from the contact 18a are elastically separated by a gap G.

Thus, when the check contact plate 21 is operated by pushing the knob 16 in the direction of the arrow C in FIG.
3d, and then the front surface 21c of the contact plate 21 contacts the back surface 18c of the movable element 18, moves further in the direction of the arrow C while pressing, and the contact 18a of the movable element 18 touches the printed circuit board 1.
The fixed contacts 13b, 13c1, and 13d of the printed circuit board 13 are formed to be connected to each other by being pressed against the fixed contacts 13b, 13c of the printed circuit board 13, respectively, and the gap G corresponds to the stroke of the button operation of the knob 16. It is what it is.

Fixed contacts 13b1 and 13c corresponding to the two contacts 18a of the movable element 18 and a fixed contact 13d corresponding to the contact 21b of the contact plate 21 for checking are printed on the upper surface of the printed circuit board 13. Further, the wiring portions of the fixed contacts 13b, 13c and 13d are connected to the main body 8.
Lead wires 22, 23, and 24 are connected to the respective wiring portions.

The fixed contacts 13b1 and 13c are printed to face the two contacts 18a when the mover 18 is at the limit position for clockwise rotation, and the fixed contacts 13d
The contact plate 21 is also printed so as to face the contact plate 21 for checking when the movable element 18 is at the limit position for clockwise rotation as shown in FIG.

Reference numeral 25 denotes a rubber ring having an X-shaped cross section.
The knob 16 is fitted into the outer circumferential groove 11d of the knob 16 to reliably prevent water from entering from the outside, and is preferably filled with grease or the like to make the rotation of the knob 16 smooth.

Reference numeral 26 denotes a sleeve-shaped rubber cover, one end of which is tightly fitted into the cylinder 11 and the other end into the strip IR 16a of the knob 16, respectively.

In addition, as shown in FIG. 5, the letters SET and OFF are displayed at the end of the flange 11 of the cylinder 11 near the knob 16 by 45 degrees in the circumferential direction, and the letters SET and OFF are displayed at the end of the flange 11 near the knob 16.
A triangular mark 16b is displayed on the outer end surface.

The triangular mark 16b faces the character SET when the knob 16 is at the limit position for clockwise rotation, and the triangular mark 16b faces the character OFF when the knob 16 is at the limit position for counterclockwise rotation. It is opposite to the position.

The tire pressure sensor according to the present invention is connected to a tire pressure warning device via the lead wires 22, 23 and 24, for example, as shown in FIG.

27 is a dry battery, 28 is a rotation detection switch provided on a road wheel, etc., 29 is an alarm buzzer, 30 is a transistor,
31 is an oscillation circuit such as an astable multivibrator, 32 and 33 are resistors, and 34 is a capacitor.

With the above configuration, the tire air pressure sensor according to the present invention operates as follows to activate the tire air pressure alarm device.

Normally, the knob 16 is set at the limit position for clockwise rotation, and the triangular mark 16b is opposed to the position of the display character SET on the cylinder 11, as shown in FIG.

At this time, the two contacts 18a of the mover 18 are connected to the fixed contact 13.
b and 13c, and also 1, contact plate 2 for checking
The first contact 21b is provided opposite to the fixed contact 13d.

As mentioned above, when the tire air pressure sensor is in normal use, when normal tire air pressure is introduced into the chamber 8e of the main body 8, the center portion of the rubber tire flamm 12 is moved by the spring 20.
The mover 18 is pushed and displaced toward the right in FIG.
The contact 18a is separated from the fixed contacts 13b and 13c,
Further, the contact 21b of the check contact plate 21 is also separated from the fixed contact 13d.

Therefore, the tire pressure warning device shown in FIG. 7 is not activated, and the vehicle driver knows that the tire pressure is normal.

Next, when the tire pressure sensor is in normal use,
When the tire air pressure decreases below the specified value, the center portion of the rubber diaphragm 12 is reversed by the spring 20 and becomes the state shown in FIG. 3, and the two contacts 13b of the mover 18
and 13c, respectively, to establish electrical continuity between the fixed contacts 13b and 13c.

At this time, if the vehicle is running, the tire pressure warning device shown in FIG. 7 issues a warning with a buzzer sound, and if the vehicle is stopped, the warning buzzer does not sound.

That is, when the vehicle is running as in the former case, the rotation detection switch 28 is closed, and the positive terminal of the oscillation circuit 31 is connected to the resistor 32, the rotation detection switch 28, the fixed contact 13c1, the mover 18, and the fixed contact 13b. It is connected to the positive terminal of the dry cell battery 27, and the positive terminal of the alarm buzzer 29 is connected to the positive terminal of the dry cell battery 27 via the fixed contact 13C1 mover 18 and the fixed contact 13b, and thus the oscillation circuit 31 oscillates by its operation. The output is output to the base of the transistor 30, and the transistor 30 is turned on and off to generate an alarm buzzer 2.
9 sounds intermittently.

Therefore, the vehicle driver can be informed of an abnormality in the tire air pressure by the activation of the warning buzzer 29.

In addition, when the vehicle is stopped as in the latter case, the rotation detection switch 28 is open and the positive terminal of the oscillation circuit 31 is not connected to the positive terminal of the dry cell battery 27 and does not output, so the transistor 30 is not turned on and the alarm buzzer is activated. 29 is not activated.

Therefore, it is possible to prevent the dry battery 27 from being completely exhausted due to the warning buzzer 29 continuing to sound due to a drop in tire air pressure during parking.

Next, after the driver becomes aware of the decrease in tire pressure due to the activation of the warning buzzer 29, the driver stops the vehicle, gets out of the vehicle, and switches the rotation detection switch while confirming which wheel's tire pressure has decreased. 28 is turned off, the delay circuit composed of a resistor 33 and a capacitor 34 continues to operate the oscillation circuit 31 for a time corresponding to its time constant and sounds the alarm buzzer 29, so the above confirmation cannot be performed during this time. Ru.

After that, if the driver is unable to immediately replenish the tire pressure for the specified wheel, the driver should move the knob 16 4 to the left.
By rotating the movable element 18 by 5 degrees, the contact 18a of the movable element 18 is separated from the fixed contacts 13b and 13c, and the operation of the tire pressure warning device can be stopped.

That is, by rotating the knob 16 from the limit position for clockwise rotation to the limit position for counterclockwise rotation, the contact portion 18a of the movable element 18 slides on the upper surface of the printed circuit board 13 and comes into contact with the fixed contacts 13b and 13c. At this time, the triangular mark 1 on knob 16
6b corresponds to the position of the display character OFF on the flange lla of the cylindrical body 11.

Next, when checking whether the circuit and various elements of the tire pressure alarm device are normal or not, when the tire pressure sensor is in normal use, move the knob 16 against the spring 20 to the third position. The rotation detection switch 28 is pushed in the direction of arrow C in the figure, and the contact 21b of the check contact plate 21 is brought into contact with the fixed contact 13d, and the contact 18a of the movable element 18 is brought into contact with the fixed contacts 13b and 13C. Irrespective of whether the tire pressure alarm circuit is open or closed, the tire pressure alarm circuit is arbitrarily closed, and if there is an abnormality, the alarm buzzer 29 does not sound, so that the vehicle driver can be informed of this abnormality.

The tire air pressure sensor according to the present invention has the above-mentioned configuration and operation, and has the following effects.

(a) By configuring the mover to be a pressed product rather than a machined product, it has become possible to improve component accuracy, facilitate miniaturization, and reduce manufacturing costs.

(b) By configuring the hollow shaft with an insulator, it is possible to use resin molding rather than conventional cutting, and this also makes it easier and more stable to fix the contact plate, making it possible to significantly reduce machining. This facilitates cost reduction, miniaturization, and improvement in accuracy.

(c) With the configurations of items (a) and (b) above, it is possible to provide a tire air pressure sensor that is smaller, lighter, less expensive, and more practical.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional tire air pressure sensor. FIG. 2 is a perspective view showing a component configuration of a movable side contact portion of a conventional tire air pressure sensor. FIG. 3 is a sectional view of a tire air pressure sensor according to the present invention. FIG. 4 is a sectional view taken along arrow line A-A in FIG. 3. FIG. 5 is a plan view taken along the arrow line B--B in FIG. 3. FIG. 6 is a perspective view showing the component configuration of the movable side contact portion of the tire air pressure sensor according to the present invention. FIG. 7 is an electrical circuit diagram of a tire pressure warning device using a tire pressure sensor according to the present invention. 1.10...Air valve, 3,18...
・Mover, 4.13...Printed circuit board, 5,1
4...Hollow shaft, 6,21...Contact plate,
Death...Body, 11...Cylinder, 12...
...Rubber diaphragm, 13b, 13c, 13d...
...Fixed contact, 16...Knob, 22.23
．． 24...Lead wire.

Claims (1)

[Scope of utility model registration request] A main body attached to the air valve of a tire via a ring nut on the circumference of one side, an insulating cylinder fixed to the other side of the main body, a diaphragm held between the cylinder and the main body, A printed circuit board on which fixed contacts are printed, and an arm that is inserted into the cylinder so that it can move forward and backward and rotate within a predetermined angle, and has a knob at one end and a contact at an annular outer periphery at the other end. A hollow shaft made of resin molded to which a check contact plate made of conductive elastic material is fixed, and a thin plate made of conductive material are bent into a U-shape, with a movable pin in the center. Contact points are provided in the hole to be fitted and both sides of the hole, and both bent ends thereof are inserted into recesses formed in the other peripheral wall of the hollow shaft so as to be able to move forward and backward, thereby rotating. It consists of a movable element that is engaged with the hollow shaft in the direction, and a movable pin that fits the movable element into a circumferential groove at one end with a tapered outer diameter and whose other end is driven by pressure by displacement of a diaphragm. A tire pressure sensor characterized by: